Flicker-free lighting for broadcast and slow motion

Under standard frame rates most LED floodlights look stable. Under a super-slow-motion camera running at hundreds or thousands of frames per second, the same light can pulse visibly from frame to frame. For a broadcaster that is a replay ruined.

Where flicker comes from

An LED's light output follows its drive current. If the driver lets current ripple at twice the mains frequency, or uses low-frequency PWM for dimming, output ripples too. The eye integrates it; a high-speed camera does not.

Measuring it

• Flicker percentage (percent modulation) — the depth of the ripple between maximum and minimum output.
• Flicker index — accounts for the shape of the waveform as well as the depth.

For high-speed broadcast, the target is a modulation low enough to be invisible at the replay frame rate the broadcaster uses. Federations and broadcasters publish their own requirements; check them for each project.

What to specify

• Constant-current drivers with low output ripple across the whole dimming range — not only at full power.
• Dimming by current reduction or high-frequency PWM, not low-frequency PWM.
• Test data for flicker at dimmed levels, because broadcast scenes are often run below maximum.

Before you sign off

Ask for a camera test. A short clip at the broadcaster's slow-motion frame rate, under one production luminaire at the intended dimming level, settles the question faster than any datasheet.